Stem cells can be expanded from a few donor cells in a cell expansion apparatus. The resulting multiplied cells can be used to repair or replace damaged or defective tissues. Stem cells have broad clinical applications for a wide range of diseases. Recent advances in the area of regenerative medicine have demonstrated that stem cells have unique properties such as high proliferation rates and self-renewal capacity, ability to maintain an unspecialized cellular state, and the ability to differentiate into specialized cells under particular conditions.
As an important component of regenerative medicine, bioreactor systems play an important role in providing optimized environments for cell expansion. The bioreactor provides efficient nutrient supply to the cells and removal of metabolites, as well as furnishing a pysiochemical environment conducive to cell growth. In particular, foreign cells, such as air-borne pathogens, must be excluded from the cell-growth areas of the bioreactor. At the same time it is important to be able to obtain samples of the expanding stem cells to determine how much cellular growth has taken place. There remains a need for improved apparatus and methods for hermetically sampling expanding cellular material from cell-growth areas of a bioreactor, without environmental contamination.